Over 300,000 Must Prove Eligibility or Lose Health Care

WASHINGTON — More than 300,000 people who bought subsidized health insurance under the Affordable Care Act could lose it next month if they do not provide proof that they are living in the United States legally, the Obama administration said Tuesday.

The administration has been trying to resolve questions about the eligibility of hundreds of thousands of people who signed up for private health plans through the new insurance exchanges and qualified for federal subsidies to help with the cost. Most of the discrepancies involve citizenship, immigration status or income.

About 450,000 cases with discrepancies related to citizenship or immigration status have been resolved, and an additional 210,000 are “in progress,” according to Marilyn B. Tavenner, the administrator of the Centers for Medicare and Medicaid Services, which runs the federal exchange. But about 310,000 people have not responded to calls, letters and emails asking about inconsistencies between citizenship or immigration data on their application forms and government records.

On Tuesday, the administration sent another round of letters asking these people to submit more documentation by Sept. 5. If they fail to do so, the letters said, they will lose their coverage by Sept. 30. The federal exchange will also try to reach them again by phone and email, and it is asking consumer assistance groups to help deliver the message.

“We want as many consumers as possible to remain enrolled in marketplace coverage,” Ms. Tavenner said in a statement, “so we are giving these individuals a last chance to submit their documents before their coverage through the marketplace will end.”

Almost half of the unresolved cases involving immigration or citizenship status are in Florida and Texas, which have large Hispanic populations.

The health care law allows only “lawfully present” immigrants to buy insurance through the new exchanges. They include immigrants with green cards, refugees, people in the United States on student or worker visas, and several other categories.

People who reported incomes that do not match federal records will be contacted later, according to a news release from the Centers for Medicare and Medicaid Services. The 14 states running their own exchanges are handling data inconsistencies separately.

Republicans have repeatedly accused the administration of being careless about verifying the income and eligibility of people who applied for insurance subsidies. And a recent report by the inspector general for the Department of Health and Human Services said the exchanges did not have adequate safeguards “to prevent the use of inaccurate or fraudulent information when determining eligibility.”

But another inspector general report pointed out that the inconsistencies did not necessarily mean that applicants had intentionally provided wrong information. Some federal data appeared to be inaccurate or old, it found, and the federal eligibility system sometimes failed for technical reasons.

A version of this article appears in print on , on Page A13 of the New York edition with the headline: Over 300,000 Must Prove Eligibility or Lose Health Care. Order Reprints | Today’s Paper | Subscribe